Developing now cellphone searches and the Supreme Court decision today that police officers will need to obtain a warrant to search the cell phone of a person. Under arrest I'm Michelle Franzen in New York just one of the several rulings handed down today. This one a blow to officers who wanted more latitude to search cell phones. We have many questions on this decision here to help us ABC news chief legal affairs -- -- -- Dan Abrams and ABC news consultant. And former new York city police commissioner Ray Kelly but we want to begin with ABC news correspondent Terry Moran who was at the Supreme Court this morning when -- ruling came down. -- brake to -- down for. Well Michelle this is the most sweeping. Ruling on privacy in the digital age that the court has handed down and it was remarkable because we're used to this court. Being sharply divided liberals and conservatives. And this was in its result. Unanimous. -- opinion and a sweeping one as well in this case there were two defendants who had been arrested. And the police officers who arrested them got access to their Smartphones. And found. Important evidence so on the one hand. The -- is a member of a gang and they found evidence of that. Because they went through his videos so exactly what what do you think we keep our lives are on the cell phones -- on the Smartphones. And the notion that that the police -- Merely upon arrest could then go through the rest of your life -- you arrested for speeding excessively. Very excessively. Or -- there was a bench warrant out for you for some reason that they could go through your cell -- get access to all that we put on it. Was clearly an ominous one for this court. The court was emphatic. That. In the digital age. This is different this is different -- searching a suspect in rifling his wallet this is something. That the founders could not enforcing but they believe. Fit squarely within that old Fourth Amendment of the constitution protects us from unreasonable searches and seizures. And Terry you mentioned that it is a very rare for justices to be unanimous in this decision. So in addition to the privacy and keeping up with the technology what do you think it was about these cases that. Resonated with this and led to consensus. You know we. Often see the justices Supreme Court as kinda clueless about new technology some of them -- really don't even really have any idea what's that what's going on online these days. But on this what it -- like everybody vast numbers of people. Have Smartphones chief Justice Roberts noted in in his opinion that 12% of Americans it. Have answered pollsters that they actually use the cellphone in the show how war. -- that's how you did that's how essential they are our lives and the justices got that they're also one of the draw a very bright line against the government. -- government had argued. -- look on an arrest the police can search. Four certain things without a warrant. If it's there's a risk that the suspect might be about to destroy evidence or that there might be something dangerous. On the suspect. That's where they get directly through the wall it. And the government said look at you can go to somebody's wallet -- to go through a cell -- there's really no difference. And chief just rough Justice Roberts did did pretty pointedly that's like say there's no difference between riding a horse and flying to the moon sure both -- get from point a to point B. We -- in a different era now it seems they really sensed that and one of the draw bright line around. Thanks Terry Moran in Washington. And now we want to bring ABC's chief legal affairs anchor Dan it runs and ABC news consultant Ray Kelly former police commissioner New York City. Dan let's start with you are you surprised by the legal ruling in this. No I'm not surprised that the only thing it was a little bit surprising. Was it the -- -- put it -- sweeping nature of this ruling there there could have been a middle ground here there could have been ways for them to compromise to some degree. As some of the questions. Indicated that they might win this was in oral argument. But when this ruling came down it was clear. That they wanted to draw this this line. -- to say you simply can't view a cell phone. Like Q do you other things in connection what they call being an. Incident to the arrest as Terry said going through an address book. Or other items that are found when someone is arrested now the court also recognized that this is gonna have a negative impact on law enforcement. And -- mr. commissioner Kelly available to talk about that but -- chief Justice Roberts made it very clear he recognized that there was going to be eight price to pay. When it came to law enforcement on this that they wouldn't immediately be able to you get access to information that could help. That they would have to go get a warrant. -- but when it came to things like destroying evidence the court specifically said there ways to deal with the you can still sort of take the phone. And put it in. In a bag so that it can't. The transmit any more information. There are ways for you to still collect the evidence. And then go get a war. There's something else with -- -- is important here which is called an oxygen circumstance which is. Let's say that there is an imminent terrorist attack or something like that -- the court is still recognizing. That in those sorts of incidents. You may be able to get access to something like this but you sure the baby better be able to defend yourself later. When it comes up in court so. Bottom line though this is a a really sweeping decision and the unanimity I think of the court also adds to that. Power and -- and -- certainly chief Justice Roberts saying that privacy comes at a cost. Ray Kelly -- police officers and law enforcement agencies see this as a -- sit there efforts. But -- -- -- or enforcement. More difficult -- no question about that. But. Law enforcement police officers. Have adapted to the court's ruling in the past and I think you'll see that in this instance you'll see. It being more expeditious to you get a warrant they'll be Georgia's that'll be available on a 24 hour basis that that sort of thing so. I think it as I say it's going to make it more difficult but I I think you'll see a fairly quickly that the law enforcement will be able to. To handle it and and has been said there are -- circumstances. That. May apply in in certain circumstances where you can in fact. Search the follow. And you have been on that side of the search get an idea described the path now to obtain a warrant. If law enforcement arrest somebody and they need access to that cell phone information -- case well what would happen. Is that -- big George would be available you may get a warrant over the telephone it depends. On what court what jurisdiction where we're talking about it was a a decision about GPS devices. In terms of tracking a car the police were able -- just put one of those devices on a car without a warrant. The court said no you need a warrant to do it and in fact the -- courts have. Adapted to getting those warrants Alan -- and it expeditiously. -- I think that's what you'll see it in this a situation. Yes it's going to slow things down. But probably not appreciable. And it. And -- those emergency situations when time is critical working a case they still have. The means to adapt and get that -- in a timely fashion. Well yes we're going to see because apple developed through -- -- as well but I think that the the court left open that that possibility. Daniel when -- -- -- that there's a recognition in this opinion. -- beyond cellphones right I mean this isn't just about looking your phone. The point that the court is making is so much of us keep so much of our lives. On our mobile devices. That this is not the same as just an address book the court pointed out. Because there is so much information so much private personal information. All and any particular person's. Cell phone mobile device whatever you want to call it. Such that there are six significant. Privacy interests. That coming to play. And it was interesting to hear and read read. How the court recognized that -- in such a major way in this opinion can you break that down for the two cases that were brought before the Supreme Court on this issue. We'll look at the court is saying it affected the principle is the same. In both of these instances right. Which is that yes they're different kinds of cases. About how they got access to the phone -- what kind of information they were able to get. From the phone one of them leads them to other information one of the -- into a home etc. But the bottom line is that the principle remains the same and that is when you arrest someone he does not mean you can immediately. Accessed their phone you need to get award and the court you know laid out all of these scenarios and then had a sentence that said. It just means you need to get award. And and that's the key thing here does not mean that. In the end that you can't get access to these people's cellphones is just talking about. How you go about getting that access and the court making it clear. That this is different this is not one of these incidents where we're just gonna say that in the context of an arrest. A cell phone and mobile device is just another item there that you can check out to make sure there's no threat there's no issue with destroying evidence. This kind of device is different and special. And the court is recognized them. And following the ruling of the ACLU spoke out in a statement Stephen. ACL use that quote. By recognizing that the digital revolution has transformed our expectations of privacy. Today's decision is itself revolutionary. And we'll help to protect the privacy rights of all Americans. And are there other great areas still yet to be decided whether in the legal process or out on the street following -- supreme court's ruling on cellphone searches. They're -- -- and you know it'll be developed through case -- of other cases that. Ultimately may go to the Supreme Court -- certainly it. You know it and I in this instance -- to have a nine to nothing. The ruling shows how strong the obviously the court -- the navel waiting for. A case like this but they'll always be on the street variations that. Will be determined on the road. -- for the court system. And Dan what about the legal avenue -- this. Look he did there's going to be a liberal Supreme Court decisions right end -- extending and other cases and they end up being cited. In other areas and there's no question because. The way that. The the lines that still have to be drawn. With regard to the digital revolution. This case will be cited down the road. On the four people advocating one position or another. But because it was not enough. Because. That the ruling was so sweeping I think it could have an impact on other types of cases. Where they -- where the the the court will ultimately say. In connection with. This new case look at what we did previously here we made it very clear that there is this this privacy interest that is at play that -- different. In the digital age that his previously existed and I think that that the death that's the way that it may be used as precedent. Dan one last question you mentioned new cases what about cases where people -- -- convicted. Witness police search will look. They could certainly now appeal and say that the supreme court's ruling makes it clear. That that their particular case I should be thrown out and that's always. And -- -- comes up. When the Supreme Court issues a ruling of this sort. I'd be interested -- -- commissioner's point of view as to whether he thinks that that the impact it's going to be. Major in terms of the effect it will have on other cases. Obviously that remains to be seen but. I think -- you'll see. Appeals mean phones have been -- very very valuable source of information to police for. Many years so you're going to see. I think at least an attempt to to overturn. Decisions and you'll see that fairly soon. The remember it'll just be the cases where you've got similar facts -- doesn't mean any time the police got information from the -- It would mean any time the police got information from a phone. In connection with an arrest without -- -- -- And -- that became a crucial part of the case against someone. Those are the kinds of cases where you might see. Potentially successful appeal. Very interesting day ABC news legal analyst Dan Abrams and ABC consultant Ray Kelly thanks so much for joining us. On this big ruling today. Keep up with the story in real time by downloading the ABC news -- -- starring the story for those exclusive updates on the go. For now I'm Michelle Franzen -- New York.

This transcript has been automatically generated and may not be 100% accurate.